This invention relates to a system and to a method for the manufacture and production of dies and, more specifically, but not exclusively, to a system and to a method for the production and manufacture of dies to be utilised in a wide range of production processes, such as injection moulding, gravity die casting and the like.
A method and a system for producing a metal article such as a die is disclosed in applicant""s South African Patent Application No. 99/2209, which is incorporated herein in its entirety by reference.
The disclosed method of producing a die includes the steps of:
providing a CAD model of the die to be formed;
rapid prototyping a three-dimensional patterns of the die from the CAD model thereof;
producing mould of the die from the three-dimensional pattern thereof; and
casting the die from the mould.
Whilst the applicant""s method is effective and allows for the rapid production of new tooling, a number of difficulties have emerged. In particular, the castings produced in the casting step of the method exhibit a degree of metal shrinkage which is difficult to predict and which affects the accuracy of a final article which is to be produced by means of the die.
Further, texturing of the surface of such dies is difficult and costly to achieve. WO9939889 discloses a thermally efficient mold apparatus and method and U.S. Pat. No. 5,823,778 discloses an imaging method for fabricating dental devices. The inventions of these documents do not assist in resolving the above problems.
It is an object of this invention to provide a system and a method for the production so of a die for moulding or forming a metal article which will, at least partially, alleviate the abovementioned difficulties and disadvantages.
In accordance with this invention there is provided a method for producing a die, comprising the steps of:
providing a reference CAD model of the die of desired dimensions;
producing an oversized casting of the die from a mould thereof;
measuring the actual dimensions of the oversized casting;
comparing the measured dimensions of the oversized die against the reference CAD model; and
ablating the oversized casting until its dimensions are substantially the same as those of the reference CAD model.
Further features of the invention for producing an oversize casting of the die by the steps of:
providing an oversize CAD model of the die;
including in the oversize CAD model a number of reference points sufficient to define a three-dimensional co-ordinate system relative to the CAD model;
rapid prototyping a three-dimensional pattern of the die from the oversize CAD model thereof;
producing a mould of the die from the three-dimensional pattern thereof; and
casting the oversize die from the mould.
Still further features of the invention provide for measuring the actual dimensions of the oversize casting by the steps of:
imaging the oversize casting to obtain the co-ordinates of the surface of the oversize casting relative to the three dimensional co-ordinate system defined by the number of reference points on the casting; and
converting the co-ordinates into a measured CAD model.
Yet further features of the invention provide for ablating the oversize casting by any one of the methods of laser ablation, machining or spark erosion, and for imaging the oversize casting by means of a laser-based, alternatively a contact-based imaging system.
There is also provided for the method to include the additional step of texturing at least a portion of the surface of the casting; and
texturing at least a portion of the surface of the casting by:
providing a reference CAD model of the desired texture to be applied to the surface of the casting;
identifying the portion of the surface of the casting to be textured as a function of the co-ordinates of each one of the number of reference points on the casting; and
ablating the identified portion of the surface of the casting in accordance with the reference CAD model of the desired texture to be applied to the casting.
There is further provided for ablating the portion of the surface of the casting by laser ablation.
There is further provided for including at least one integral cooling pathway through the oversize casting, and for the integral cooling pathway to also include a hollow back and a baffle to direct the flow of a coolant therethrough.
The invention extends to a system for producing a die comprising:
means for generating a reference CAD model of a die of desired dimensions to be produced;
a production facility arranged to produce an oversized casting of the die from a mould thereof;
measuring means for measuring the actual dimensions of the oversized casting;
comparator means for comparing the measured dimensions of the oversized die against the reference CAD model; and
an ablating facility adapted to machine the oversized casting until its dimensions are substantially the same as those of the reference CAD model.
There is further provided for the production facility to include:
means for generating an oversize CAD model of the die, containing a number of reference points sufficient to define a three-dimensional co-ordinate system relative to the CAD model;
a rapid prototyping facility arranged to produce a three-dimensional pattern of the die from the oversize CAD model thereof; and
a production means for producing a mould of the die from the three-dimensional pattern thereof, and for casting the die from the mould thereof.
There is still further provided for the measuring means to be an imaging system adapted to obtain the co-ordinates of the surface of the oversize casting relative to the three-dimensional co-ordinate system defined by the number of reference points on the casting, and to convert the co-ordinates into a measured CAD model.
There is yet further provided for the ablating facility to be any one of a laser ablating facility, a machining facility or a spark erosion facility and for the imaging system to be a laser-based, alternatively a contact-based imaging system.
There is also provided for the system to include a texturing means for texturing at least a portion of the surface of the casting, and for the texturing means to include:
means for generating a reference CAD model of a desired texture to be applied to the surface of the casting;
identification means for identifying the portion of the surface of the casting to be textured, as a function of the co-ordinates of each one of the number reference points on the casting; and
an ablating facility adapted to ablate the identified portion of the surface of the casting in accordance with the reference CAD model of the desired texture to be applied to the casting.
There is also provided for the ablating facility to be a laser machining facility.
There is further provided for the oversize casting to include at least one integral pathway therethrough and for the pathway to include a hollow back and a baffle to direct a flow of coolant therethrough.